(1) Field of the Invention
The present invention relates to an optical information recording/reproducing apparatus which records, as page data, information of a pattern of interference between signal light and reference light in an optical information recording medium and reproduces the information from the optical information recording medium.
(2) Description of the Related Art
As a hologram recording/reproducing technique, there is, for example, JP-A-2014-32727. In this publication, it is described that an object is “to provide a hologram optical pickup apparatus and a light information recording/reproducing apparatus which can perform high-quality data reproduction and high-speed recording/reproduction by reducing light loss and improving light use efficiency”. Also, it is described that “the resolution means includes: a light source that emits a light beam; a splitting element that splits the light beam emitted from the light source into a signal light beam and a reference light beam; an angle changing element that changes the angle of the reference light beam incident on an optical information recording medium; a spatial light modulator that adds information to the signal light beam; an objective lens that irradiates the optical information recording medium with the signal light beam; and an imaging element that detects a diffracted light beam generated from a recording region in the optical information recording medium when the optical information recording medium is irradiated with the reference light beam”. Further, it is described that “the resolution means includes an optical element capable of shaping the light flux of the reference light beam into a desired shape and/or a desired light flux diameter, and the light flux shape and/or the light flux diameter of the reference light beam irradiating the optical information recording medium can be controlled by controlling the light flux shape and/or the light flux diameter with the optical element”.